The Panasonic AG-DV2500 tape deck contains an invalid entry in itsconfiguration ROM root directory: A leaf pointer with the undefined keyID 0 and an offset that points way out of the standard config ROM area.This caused firewire-core to dismiss the device with the generic logmessage "giving up on config rom for node id...", after which it was ofcourse impossible to access the tape deck with dvgrab or any otherprogram. https://bugzilla.redhat.com/show_bug.cgi?id=449252#c29

The fix is to simply ignore this invalid ROM entry and proceed to readthe valid rest of the ROM. There is a catch though: When the kernellater iterates over the ROM, it would be nasty having to check again forsuch too large ROM offsets. Therefore we manipulate the defective orunsupported ROM entry to become a harmless immediate entry that won'thave any side effects later (an entry with the value 0x00000000).